2026 MECH 321 LAB 1 Experiment TENSILE TESTING OF MATERIALS (Properties & Failure of Materials) Concordia University

2026 MECH 321 LAB 1 Experiment TENSILE TESTING OF
MATERIALS (Properties & Failure of Materials) Concordia
University

Experiment 1
Tensile Testing of Materials




MECH 321 Lab Section MI - X
Group A
Winter 2025




Prof. Sam Eskadarian



Concordia University
Montreal, QC, Canada




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,TABLE OF CONTENTS
TABLE OF CONTENTS ............................................................................... 2
LIST OF TABLES C GRAPHS ......................................................................... 2
OBJECTIVE .......................................................................................... 3
INTRODUCTION ..................................................................................... 3
EQUIPMENT.......................................................................................... 7
PROCEDURE ....................................................................................... 11
RESULTS ........................................................................................... 12
DISCUSSION........................................................................................ 24
CONCLUSION ...................................................................................... 26
REFERENCES....................................................................................... 27
APPENDIX .......................................................................................... 28



LIST OF TABLES & GRAPHS
Table 1: Experimental values
Graph 1: Engineering Stress vs. Engineering Strain – Aluminum
Graph 2: Engineering Stress vs. Engineering Strain – Brass
Graph 3: Engineering Stress vs. Engineering Strain – Steel
Graph 4: Engineering Stress vs. Engineering Strain – ABS
Graph 5: Engineering Stress vs. Engineering Strain – Aluminum (Strain Gauge Only)
Table 2: Material Properties for Aluminum
Table 3: Material Properties for Brass
Table 4: Material Properties for Steel
Table 5: Material Properties for ABS
Graph 6: True Stress vs. True Strain – Aluminum
Graph 7: True Stress vs. True Strain – Brass
Graph 8: True Stress vs. True Strain – Steel
Graph 9: True Stress vs. True Strain – ABS




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,OBJECTIVE
The objective of this experiment is to perform tensile tests on 4 different materials and use
software to record and plot stress/strain data from the experiment. The recorded data will then be
used to evaluate various parameters for each material.




INTRODUCTION
Each unique material has a unique set of parameters. These parameters include, but are
not limited to, yield strength, tensile strength, percent elongation, percent area reduction, shear
modulus, Young’s modulus, and more [1]. Various methods can be used to evaluate these
parameters, but this experiment will focus on the uniaxial tensile test [1].

A uniaxial tensile test involves applying a uniaxial load on a material with a known
cross-section and gradually increasing as the material deforms until fracture [1]. The load applied
on the cross-section is called the stress and the deformation is called the strain. Both the stress
and the strain have engineering values and true values, where the engineering values use a
constant area (initial area) and the true values use the instantaneous areas. The engineering stress
of a material can be denoted as:

σ = P/A (1.1) [1]


where P is the load and A is the cross-sectional area. Likewise, the engineering strain can be
denoted as:

ε = (Lf – L0)/L0 = ΔL/L0 (1.2) [1]

To find the true stress and strain the following equations must be used. For stress:

σtrue = σengineering * (1 + εengineering) (1.3) [1]

For strain:

εtrue = ln(1 + εengineering) (1.4) [1]

The relationship between stress and strain allows for one to calculate various unique parameters
of the tested material.




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, Figure 1: Comparative stress-strain relationships of low carbon steel and aluminum alloy and the determination of the yield
strength at 0.2% offset [1]



During a uniaxial tensile test, the stress may be removed before fracture and if the
material returns to its original size, it is said to have only elastically deformed. This portion of
deformation has a linear relationship between the stress and the strain. In contrast, if the load is
removed and the material does not return to its original size, it is said to have plastically
deformed, and the stress-strain relationship is no longer linear. In this case, some deformation
will be undone but not enough to bring it back to its original size. The amount of stress that
separates elastic and plastic deformation is called the yield strength and is simply the engineering
stress at the point where plastic deformation begins [1]. When looking at the data in figure 1, the
yield strength can be determined through 2 different methods. In the case of the steel, the yield
strength is said to be at the peak of the linear portion before the small decrease in stress occurs,
but this phenomenon does not occur with the aluminum and thus a 0.2% offset method is used.
The yield strength is found by offsetting the strain by 0.2% to the right and following the same
initial linear slope until the curve is hit, and this point is now considered the yield strength. Some
materials may experience a phenomenon called necking, where the cross-section of the material
will greatly decrease locally before fracturing in the decreased area. The stress at the point of
fracture is referred to as the fracture strength and uses engineering stress [1]. For fracture strain,
simply draw a slope parallel to the linear portion of the graph from the fracture point as every
material retracts a small amount after fracture [1].

Once the tensile test is completed, the stress/strain data can be plotted against each other
and give a similar graph to the one shown below:

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